JP6525566B2 - Zoom lens and imaging device having the same - Google Patents

Description

  The present invention relates to a zoom lens and an imaging device having the same, such as an imaging device using an imaging element such as a digital still camera, a video camera, a surveillance camera, or a broadcast camera, or an imaging device such as a camera using silver film Are preferred.

  2. Description of the Related Art In recent years, imaging devices such as digital still cameras and video cameras using solid-state imaging devices have been sophisticated, and the entire device has been miniaturized. Zoom lenses used in these devices are required to be compact, have high magnification, and have good optical performance. In order to meet such requirements, zoom lenses including lens groups having positive, negative, positive, and positive refractive powers in order from the object side to the image side are known.

  In the zoom lenses of Patent Documents 1 and 2, the second lens group is moved for zooming, and the fourth lens group is moved to perform correction and focusing of the image plane variation accompanying zooming.

  As described above, a zoom lens that performs focusing by moving a lens disposed closer to the image than the first lens group is called an inner focus zoom lens. In general, with an inner focus zoom lens, the effective diameter of the first lens group is smaller than that of a zoom lens in which focusing is performed by moving the first lens group, and it is easy to realize downsizing of the lens system.

JP-A-11-23965 JP, 2008-310222, A

  Generally, in the zoom lens, in order to miniaturize the whole system while achieving high magnification, it is sufficient to reduce the number of lenses while strengthening the refractive power of each lens unit constituting the zoom lens. However, if the refractive power of each lens surface becomes strong, the optical performance tends to deteriorate.

  In order to maintain high optical performance while realizing further high magnification and miniaturization, in a zoom lens including lens groups having positive, negative, positive, positive refractive power in order from the object side to the image side, It is important to appropriately set the refractive power of each lens group and the material of the lens.

  An object of the present invention is to provide a zoom lens which is compact and has high magnification and high optical performance, and an imaging apparatus having the same.

The zoom lens according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a third lens group arranged in order from the object side to the image side. The zoom lens comprises a fourth lens group having a refractive power, and the first lens group is immobile during zooming from the wide-angle end to the telephoto end, and at least the second lens group and the fourth lens group move and are adjacent during zooming The zoom lens according to claim 1, wherein the first lens group comprises a negative lens, a positive lens, a positive lens, and a positive lens disposed in order from the object side to the image side, the second lens group includes two negative lenses, is composed of a single positive lens, when the Abbe number of the material of the positive lens arranged in the first lens group and vd1 p, the first lens group,
74.0 <νd1p <100.0
It has a positive lens that satisfies a conditional expression, the previous SL focal length of the first lens group f1, the focal length f2 of the second lens group, the focal length of the third lens group f3, the fourth lens The focal length of the group is f4, the focal length of the entire system at the wide-angle end is fw, and the lateral magnification of the second lens group is β2t when the object at infinity is in focus at the telephoto end disposed in the second lens group The Abbe number of the material of the positive lens
-7.30 <f1 / f2 <-4.60
1.16 <f3 / f4 <1.55
3.80 <f4 / fw <6.50
−12.0 <β2t <−5.8
10.0 <νd2p <21.0
It is characterized by satisfying the following conditional expression.
In the zoom lens according to the present invention, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the third lens having a positive refractive power are disposed in order from the object side to the image side. The zoom lens comprises a fourth lens unit having a positive refractive power, and the first lens unit is stationary during zooming from the wide-angle end to the telephoto end, and at least the second lens unit and the fourth lens unit move. It is a zoom lens in which an interval between adjacent lens groups changes during zooming, and the first lens group is composed of a negative lens, a positive lens, a positive lens, and a positive lens, which are disposed in order from the object side to the image side The second lens group has three or more lens elements including at least one positive lens, and the third lens group is a positive lens, a positive lens, a negative lens disposed in order from the object side to the image side And disposed in the first lens group Been νd1p the Abbe number of the positive lens of the material, when the Abbe number of the material of the positive lens arranged on the second lens group and the Nyudi2p, the first lens group,
74.0 <νd1p <100.0
The second lens unit has a positive lens that satisfies the following conditional expression:
10.0 <νd2p <21.0
The focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the third lens group is f3, and the fourth lens group Assuming that the focal length of the lens system is f4, the focal length of the entire system at the wide-angle end is fw, and the lateral magnification of the second lens unit is .beta.2t when the object at infinity is in focus at the telephoto end.
-7.30 <f1 / f2 <-4.60
1.16 <f3 / f4 <1.55
3.80 <f4 / fw <6.50
−12.00 <β2t <−5.50
It is characterized by satisfying the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens which is compact and has high magnification and high optical performance, and an imaging device having the same.

Lens cross section of the zoom lens of Embodiment 1 at the wide angle end (A), (B), (C) Aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of the zoom lens according to Example 1. Lens cross section of the zoom lens of Embodiment 2 at the wide angle end (A), (B), (C) Aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of the zoom lens according to Example 2. Lens cross section of the zoom lens of Embodiment 3 at the wide angle end (A), (B), (C) Aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of the zoom lens according to Example 3. Lens cross section of the zoom lens of Embodiment 4 at the wide-angle end (A), (B), (C) Aberration diagrams at the wide-angle end, at the middle zoom position, and at the telephoto end of the zoom lens according to Example 4. Lens cross section of the zoom lens of Embodiment 5 at the wide angle end (A), (B), (C) Aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of the zoom lens according to Example 5. Lens cross section of the zoom lens of Embodiment 6 at the wide angle end (A), (B), (C) Aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of the zoom lens according to Example 6. Lens cross section of the zoom lens of Embodiment 7 at the wide-angle end (A), (B), (C) aberration diagrams of the zoom lens of Embodiment 7 at the wide-angle end, at the middle zoom position, and at the telephoto end Principal part schematic view of the imaging device of the present invention

  Hereinafter, the zoom lens of the present invention and an imaging device having the same will be described in detail based on the attached drawings. The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a positive refractive power. It comprises the fourth lens group. Here, the lens unit is a lens element that moves integrally during zooming, and it is sufficient if it has one or more lenses, and it is not necessary to have a plurality of lenses. The lens element refers to an integrally formed lens such as a single lens, a cemented lens in which a plurality of lenses are cemented, and a replica aspheric lens formed by laminating a resin layer on the surface of a spherical lens.

  FIG. 1 is a cross-sectional view of a zoom lens at the wide-angle end of the first embodiment. FIGS. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, of the zoom lens of Embodiment 1. FIGS. The first embodiment is a zoom lens having a zoom ratio of 24.95 and an aperture ratio of about 1.65 to 4.00. FIG. 3 is a cross-sectional view of a zoom lens at the wide-angle end of the second embodiment. FIGS. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, of the zoom lens of Embodiment 2. FIGS. The second embodiment is a zoom lens having a zoom ratio of 22.99 and an aperture ratio of about 1.65 to 3.50.

  FIG. 5 is a cross-sectional view of a zoom lens at the wide-angle end of the third embodiment. FIGS. 6A, 6B, and 6C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, of the zoom lens of Embodiment 3. FIGS. The third embodiment is a zoom lens having a zoom ratio of 27.93 and an aperture ratio of about 1.65 to 4.00. FIG. 7 is a cross-sectional view of a zoom lens at the wide-angle end of the fourth embodiment. FIGS. 8A, 8B, and 8C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, of the zoom lens of Embodiment 4. FIGS. The fourth embodiment is a zoom lens having a zoom ratio of 21.97 and an aperture ratio of about 1.65 to 3.50.

  FIG. 9 is a cross-sectional view of a zoom lens at the wide-angle end of the fifth embodiment. FIGS. 10A, 10B, and 10C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, of the zoom lens of Embodiment 5. FIGS. The fifth embodiment is a zoom lens having a zoom ratio of 23.92 and an aperture ratio of about 1.65 to 4.00. FIG. 11 is a cross-sectional view of the zoom lens at the wide-angle end of the sixth embodiment. FIGS. 12A, 12B, and 12C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, of the zoom lens of Embodiment 6. FIGS. The sixth embodiment is a zoom lens having a zoom ratio of 26.95 and an aperture ratio of about 1.65 to 4.00.

  FIG. 13 is a lens cross-sectional view of the zoom lens of Embodiment 7 at the wide-angle end. FIGS. 14A, 14B, and 14C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, of the zoom lens of Embodiment 7. FIGS. The seventh embodiment is a zoom lens having a zoom ratio of 22.97 and an aperture ratio of about 1.65 to 3.50.

  FIG. 15 is a schematic view of the essential portions of a surveillance camera provided with the zoom lens according to the present invention. The zoom lens of each embodiment is a photographing lens system used for an imaging device such as a video camera, a digital still camera, a silver halide film camera, a surveillance camera, and the like.

  In the lens sectional view, the left side is the object side (front), and the right side is the image side (rear). In the lens sectional view, Ui represents the ith lens group, where i is the order of the lens groups from the object side to the image side.

  The zoom lens of each embodiment includes, in order from the object side to the image side, a first lens unit U1 of positive refractive power, a second lens unit U2 of negative refractive power, a third lens unit U3 of positive refractive power, positive The fourth lens unit U4 has a refractive power of

  In each embodiment, SP is an aperture stop, and the aperture stop SP is disposed between the second lens unit U2 and the third lens unit U3. During zooming from the wide angle end to the telephoto end, the aperture stop SP is stationary.

  G is an optical block corresponding to an optical filter, a face plate, a low pass filter, an infrared cut filter, and the like. IP is an image plane. When a zoom lens is used as an imaging optical system of a video camera or a digital camera, the image plane IP corresponds to a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor. When a zoom lens is used as an imaging optical system of a silver halide film camera, the image plane IP corresponds to a film plane.

  In the spherical aberration diagram, Fno is an F number, and shows spherical aberration for d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm). In the astigmatism diagram, S is a sagittal image plane, and M is a meridional image plane. The distortion is shown for d-line. The chromatic aberration diagram shows the chromatic aberration at the g-line. ω is an imaging half angle of view.

  In each embodiment, as indicated by an arrow in the lens cross-sectional view, the lens unit moves during zooming from the wide-angle end to the telephoto end, and the distance between adjacent lens units changes. Specifically, in each embodiment, the first lens unit U1 does not move during zooming from the wide-angle end to the telephoto end. The second lens unit U2 moves toward the image side. In the zoom lenses of Embodiments 1 and 3 to 7, the third lens unit U3 does not move during zooming from the wide-angle end to the telephoto end. In the zoom lens of Embodiment 2, after zooming from the wide-angle end to the telephoto end, the third lens unit U3 moves to the object side, moves to the image side, and then moves to the object side again.

  In the zoom lens of each embodiment, the fourth lens unit U4 moves while drawing a convex locus on the object side during zooming from the wide-angle end to the telephoto end, and corrects the image plane variation accompanying the zooming.

  In the zoom lens of each embodiment, the fourth lens unit U4 is a focus lens unit. In the zoom lens of each embodiment, when focusing from an infinite distance object to a close distance object at the telephoto end, the fourth lens unit U4 is moved to the object side as shown by an arrow 4c in the lens cross section. The solid line 4a and the dotted line 4b in the lens sectional view respectively indicate movement loci for correcting the image plane variation accompanying zooming from the wide-angle end to the telephoto end when focusing on an infinite distance object and a near distance object. ing.

  In the zoom lens of each embodiment, shortening of the entire lens length at the telephoto end is achieved by immobilizing the first lens unit U1 during zooming. Further, by immobilizing the first lens unit U1 during zooming, it is possible to enhance the position control accuracy of the first lens unit U1.

Also, the zoom lens of each embodiment is
-7.30 <f1 / f2 <-4.60 (1)
1.16 <f3 / f4 <1.55 (2)
3.80 <f4 / fw <6.50 (3)
−12.00 <β2t <−5.50 (4)
Satisfy the following conditional expression.

Furthermore, the first lens unit U1 is
74.0 <νd1p <100.0 (5)
Have a positive lens that satisfies the conditional expression
The second lens unit U2 is
10.0 <νd2p <21.0 (6)
The following formula is satisfied:

  Here, the focal length of the first lens unit U1 is f1, the focal length of the second lens unit U2 is f2, the focal length of the third lens unit U3 is f3, the focal length of the fourth lens unit U4 is f4, and the focal length of the fourth lens unit U4 is f4. The focal length of the entire system is fw. Further, the lateral magnification of the second lens unit U2 when focusing on an object at infinity at the telephoto end is β2t, the Abbe number of the material of the positive lens disposed in the first lens unit U1 is dd1p, and the second lens unit The Abbe number of the material of the positive lens disposed in U2 is νd2p.

  Conditional expression (1) defines the ratio of the focal length f1 of the first lens unit U1 to the focal length f2 of the second lens unit U2.

  If the focal length f2 of the second lens unit U2 becomes longer than the upper limit value of the conditional expression (1), the refractive power of the second lens unit U2 becomes too weak, and the zoom operation is performed in order to realize high magnification. The amount of movement of the second lens unit U2 becomes too large. As a result, the zoom lens is unfavorably enlarged. If the focal length f2 of the second lens unit U2 becomes short beyond the lower limit value of the conditional expression (1), the refractive power of the second lens unit U2 becomes too strong, and fluctuations of various aberrations increase during zooming. Absent.

  Conditional expression (2) defines the ratio of the focal length f3 of the third lens unit U3 to the focal length f4 of the fourth lens unit U4.

  When the focal length f4 of the fourth lens unit U4 becomes short beyond the upper limit value of the conditional expression (2), the refractive power of the fourth lens unit U4 becomes too strong. As a result, the balance between the aberration correction in the third lens unit U3 and the aberration correction in the fourth lens unit U4 is broken. In particular, variations in curvature of field and astigmatism accompanying zooming increase, making it difficult to maintain high optical performance over the entire zoom range, which is not preferable.

  When the focal length f4 of the fourth lens unit U4 becomes longer than the lower limit value of the conditional expression (2), the refractive power of the fourth lens unit U4 becomes too weak. As a result, the amount of movement of the fourth lens unit U4 during focusing and zooming increases, which causes an increase in the overall lens length, which is not preferable.

  Conditional expression (3) defines the ratio of the focal length f4 of the fourth lens unit U4 to the focal length fw of the entire system at the wide-angle end.

  When the focal length f4 of the fourth lens unit U4 becomes long beyond the upper limit value of the conditional expression (3), the refractive power of the fourth lens unit U4 becomes too weak. As a result, the amount of movement of the fourth lens unit U4 during focusing and zooming increases, which causes an increase in the overall lens length, which is not preferable.

  When the focal length f4 of the fourth lens unit U4 becomes short beyond the lower limit value of the conditional expression (3), the refractive power of the fourth lens unit U4 becomes too strong. As a result, the variation of curvature of field and astigmatism accompanying zooming increases, which is not preferable.

  Conditional expression (4) defines the numerical range of the lateral magnification β2t of the second lens unit U2 when an object at infinity is in focus at the telephoto end.

  If the lateral magnification β2t of the second lens unit U2 at the telephoto end becomes lower than the upper limit value of the conditional expression (4), it is not preferable because it becomes difficult to realize high magnification. When the lateral magnification β2t of the second lens unit U2 at the telephoto end becomes high beyond the lower limit value of the conditional expression (4), the position sensitivity of the second lens unit U2 becomes too high, and manufacturing errors easily occur. Unfavorable.

  Conditional expression (5) defines the numerical range of the Abbe number dd1p of the material of the positive lens disposed in the first lens unit U1.

  If the Abbe number dd1p of the material of the positive lens disposed in the first lens unit U1 exceeds the upper limit value of the conditional expression (5), axial chromatic aberration is excessively corrected, and high optical performance is maintained. Unfavorable because it becomes difficult. If the Abbe number dd1p of the material of the positive lens disposed in the first lens unit U1 decreases beyond the lower limit value of the conditional expression (5), it becomes difficult to sufficiently correct axial chromatic aberration, which is not preferable. .

  Conditional expression (6) defines the numerical range of the Abbe number dd2p of the material of the positive lens included in the second lens unit U2. In general, axial chromatic aberration is likely to occur particularly at the telephoto end when attempting to achieve a high magnification of the zoom lens. Here, axial chromatic aberration can be effectively corrected by disposing a positive lens using a material of high dispersion in the second lens unit U2 of negative refractive power.

  If the Abbe number dd2p of the material of the positive lens included in the second lens unit U2 exceeds the upper limit value of the conditional expression (6), it becomes difficult to sufficiently correct axial chromatic aberration, which is not preferable.

  If the Abbe number dd2p of the material of the positive lens included in the second lens unit U2 decreases beyond the lower limit value of the conditional expression (6), axial chromatic aberration is excessively corrected, and fluctuation of lateral chromatic aberration associated with zooming Is not preferable because the

  In each embodiment, as described above, each element is appropriately set so as to satisfy the conditional expressions (1) to (6). As a result, it is possible to obtain a zoom lens that is compact and has high magnification and high optical performance.

In each embodiment, preferably, the numerical ranges of the conditional expressions (1) to (6) are set as follows.
-6.60 <f1 / f2 <-5.20 (1a)
1.20 <f3 / f4 <1.45 (2a)
3.82 <f4 / fw <4.70 (3a)
−10.00 <β2t <−5.85 (4a)
76.0 <νd1p <96.0 (5a)
15.0 <νd2p <19.0 (6a)

More preferably, the numerical ranges of the conditional expressions (1) to (6) may be set as follows.
−6.42 <f1 / f2 <−5.50 (1b)
1.21 <f3 / f4 <1.37 (2b)
3.84 <f4 / fw <4.35 (3 b)
−9.30 <β2t <−5.50 (4b)
81.0 <νd1p <90.0 (5b)
16.0 <νd2p <18.0 (6b)

Furthermore, in each embodiment, it is more preferable to satisfy one or more of the following conditional expressions.
nd 2 n 1> 1.900 (7)
0.070 <(TL / f1) / (ft / fw) <0. 100 (8)
0.95 <(TL / φt) / (ft / fw) <1.20 (9)
1.30 <BFw / fw <4.00 (10)
21.0 <β2t / β2w <45.0 (11)
1.30 <.beta.4 t / .beta.4 w <2.60 (12)
0.000 <L1w / TL <0.020 (13)
0.000 <L2t / TL <0.050 (14)

  Here, the refractive index based on the d-line of the lens disposed closest to the object side of the second lens unit U2 is nd2 n1, the lens surface closest to the object side of the first lens unit U1 to the image plane on the optical axis The distance is TL, the focal length of the entire system at the telephoto end is ft, and the photographing half angle of view at the telephoto end is ωt. In addition, when the back focus at the wide-angle end is BFw, the lateral magnification of the second lens unit U2 is β2 w when focusing on an infinite distance object at the wide-angle end, and The lateral magnification of the fourth lens unit U4 is β4w. Furthermore, the lateral magnification of the fourth lens unit U4 when focusing on an object at infinity at the telephoto end is β4t, and the distance between the first lens unit U1 and the second lens unit U2 at the wide angle end on the optical axis is L1w, The distance between the second lens unit U2 and the third lens unit U3 on the optical axis at the telephoto end is L2t.

  The conditional expression (7) defines a numerical range of the refractive index nd2 n1 based on the d-line of the negative lens disposed on the most object side of the second lens unit U2. By arranging a negative lens on the most object side of the second lens unit U2 and using a material of high refractive index for the negative lens, the principal point position of the second lens unit U2 can be moved to the object side. Thereby, the entrance pupil position can be moved to the object side, and the front lens effective diameter can be reduced.

  If the refractive index nd2n1 based on the d-line of the negative lens disposed on the most object side of the second lens unit U2 becomes lower than the lower limit value of the conditional expression (7), many aberrations occur in all zoom regions Also, this is not preferable because the front lens effective diameter increases.

  Conditional expression (8) defines the ratio of the distance TL on the optical axis from the lens surface closest to the object side to the image plane of the first lens unit U1 and the focal length f1 of the first lens unit U1.

  When the focal length f1 of the first lens unit U1 becomes short beyond the upper limit value of the conditional expression (8), the refractive power of the first lens unit U1 becomes too strong, and various items generated inside the first lens unit U1. Aberrations increase. In particular, axial chromatic aberration or the like generated in the first lens unit U1 is enlarged by the optical system of the second lens unit U2 and subsequent units, which makes it difficult to obtain good optical performance for the entire zoom lens, which is not preferable.

  Further, when the distance TL on the optical axis from the lens surface on the most object side of the first lens unit U1 to the image plane becomes long beyond the upper limit value of the conditional expression (8), downsizing of the zoom lens is realized. Is not preferable because it becomes difficult.

  If the focal length f1 of the first lens unit U1 becomes longer than the lower limit value of the conditional expression (8), the refractive power of the first lens unit U1 becomes too weak, and the downsizing of the entire lens system can be realized. Unfavorable because it becomes difficult.

  Further, if the distance TL on the optical axis from the lens surface closest to the object side of the first lens unit U1 to the image plane becomes short beyond the lower limit value of the conditional expression (8), the refractive power of each lens unit is strengthened. It is not preferable because it becomes necessary to make it difficult to suppress fluctuations of various aberrations associated with zooming.

  Conditional expression (9) defines the ratio of the distance TL on the optical axis from the lens surface closest to the object side to the image plane in the first lens unit U1 and the effective image circle radius φt (maximum image height) at the telephoto end. It is a thing.

  If the upper limit value of the conditional expression (9) is exceeded, the total lens length becomes too long with respect to the effective image circle radius φt at the telephoto end, which is not preferable. Further, if the distance TL on the optical axis from the lens surface on the most object side of the first lens unit U1 to the image plane becomes short beyond the lower limit value of the conditional expression (9), the refractive power of each lens unit is strengthened. It is not preferable because it becomes necessary to make it difficult to suppress fluctuations of various aberrations associated with zooming.

  Conditional expression (10) defines the ratio of the back focus BFw at the wide angle end to the focal length fw of the entire system at the wide angle end.

  When the back focus BFw at the wide angle end becomes long beyond the upper limit value of the conditional expression (10), the refractive power of the fourth lens unit U4 disposed closest to the image side becomes too weak. As a result, the amount of movement of the fourth lens unit U4 during focusing and zooming increases, which causes an increase in the overall lens length, which is not preferable. If the back focus BFw at the wide angle end becomes short beyond the lower limit value of the conditional expression (10), the distance between the fourth lens unit U4 and the image plane IP becomes too short, and it becomes difficult to arrange the optical block G etc. Is not preferable because

  Conditional expression (11) shows the lateral magnification β2w of the second lens unit U2 when focusing on an infinite distance object at the wide angle end, and the second lens unit when focusing on an infinite distance object at the telephoto end. It defines the ratio of the lateral magnification β2t of U2.

  If the upper limit value of the conditional expression (11) is exceeded, the magnification change ratio of the second lens unit U2 becomes too high, which is not preferable because the fluctuations of various aberrations increase during zooming.

  If the lower limit value of the conditional expression (11) is exceeded, the magnification change ratio of the second lens unit U2 becomes too low, which makes it difficult to realize high magnification, which is not preferable.

  Conditional expression (12) shows the lateral magnification β4w of the fourth lens unit U4 when focusing on an infinite distance object at the wide angle end, and the fourth lens unit when focusing on an infinite distance object at the telephoto end. It defines the ratio of the lateral magnification β4t of U4.

  If the upper limit value of the conditional expression (12) is exceeded, the refractive power of the fourth lens unit U4 becomes too strong, and the distance between the fourth lens unit U4 and the image plane IP becomes too short. Is not preferable because it becomes difficult.

  If the lower limit value of the conditional expression (12) is exceeded, the zooming ratio of the fourth lens unit U4 becomes too low, which makes it difficult to realize a high magnification, which is not preferable.

  The conditional expression (13) is obtained by setting the distance L1w on the optical axis of the first lens unit U1 and the second lens unit U2 at the wide angle end and the optical axis from the most object side lens surface of the first lens unit U1 to the image plane. Defines the ratio of the distance TL.

  When the distance L1w on the optical axis of the first lens unit U1 and the second lens unit U2 at the wide angle end becomes wider beyond the upper limit value of the conditional expression (13), it becomes difficult to realize miniaturization, so Absent. If the lower limit value of the conditional expression (13) is exceeded, the first lens unit U1 and the second lens unit U2 interfere with each other, which is not preferable.

  The conditional expression (14) is obtained by setting the distance L2t on the optical axis between the second lens unit U2 and the third lens unit U3 at the telephoto end and the optical axis from the most object side lens surface of the first lens unit U1 to the image plane. Defines the ratio of the distance TL.

  When the distance L2t on the optical axis between the second lens unit U2 and the third lens unit U3 at the telephoto end becomes wider beyond the upper limit value of the conditional expression (14), it becomes difficult to realize miniaturization, which is preferable. Absent. If the lower limit value of the conditional expression (14) is exceeded, the second lens unit U2 and the third lens unit U3 interfere with each other, which is not preferable.

Preferably, the numerical ranges of conditional expressions (7) to (14) are set as follows.
nd 2 n 1> 1.940 (7a)
0.074 <(TL / f1) / (ft / fw) <0.099 (8a)
0.97 <(TL / φt) / (ft / fw) <1.18 (9a)
2.00 <BFw / fw <3.00 (10a)
22.0 <β2t / β2w <43.0 (11a)
1.35 <.beta.4 t / .beta.4 w <2.50 (12a)
0.0010 <L1w / TL <0.015 (13a)
0.010 <L2t / TL <0.040 (14a)

More preferably, the numerical ranges of the conditional expressions (7) to (14) are set as follows.
nd 2 n 1> 1.950 (7 b)
0.076 <(TL / f1) / (ft / fw) <0.098 (8b)
0.98 <(TL / φt) / (ft / fw) <1.17 (9b)
2.30 <BFw / fw <2.80 (10b)
23.0 <β2t / β2w <41.0 (11 b)
1.40 <.beta.4 t / .beta.4 w <2.40 (12b)
0.0040 <L1w / TL <0.010 (13 b)
0.015 <L2t / TL <0.030 (14 b)

  In the zoom lens of each embodiment, the first lens unit U1 is composed of, in order from the object side to the image side, a negative lens, a positive lens, a positive lens, and a positive lens. The zoom lens of each embodiment is a high power zoom lens having a zoom ratio of about 20 to 30, and axial chromatic aberration generated inside the first lens unit U1 is enlarged by the optical system of the second lens unit U2 and subsequent ones. Therefore, many axial chromatic aberrations are likely to occur near the telephoto end.

  In the zoom lens of each embodiment, the axial chromatic aberration generated inside the first lens unit U1 is reduced by arranging a negative lens and three positive lenses in the first lens unit U1.

  Furthermore, in the zoom lens of each embodiment, the second lens unit U2 is composed of three or more lenses including at least two negative lenses and at least one positive lens.

  In the zoom lens of each embodiment, the refractive power of the second lens unit U2, which is a main variable magnification unit, is strengthened in order to realize high magnification. In this way, both a reduction in size and an increase in magnification of the zoom lens are achieved. Here, in order to strengthen the refractive power of the second lens unit U2, it is necessary to strengthen the refractive power of each lens included in the second lens unit U2. In the zoom lens of each embodiment, by arranging at least two negative lenses in the second lens unit U2, the negative refracting power is shared by a plurality of negative lenses, and various aberrations generated in each lens as zooming is performed. It is controlling the fluctuation.

  In the zoom lens of each embodiment, at least one lens (aspheric lens) having an aspheric lens surface is disposed in the third lens unit U3. The zoom lens of each embodiment has an aperture ratio of about 1.6 at the wide angle end, and is likely to generate spherical aberration and coma. Therefore, by arranging an aspheric lens in the third lens unit U3, generation of spherical aberration and coma is effectively suppressed.

  Subsequently, the configuration of each lens group will be described. In the zoom lens of each embodiment, the first lens unit U1 is composed of, in order from the object side to the image side, a negative lens, a positive lens, a positive lens, and a positive lens.

  In the zoom lenses of Embodiments 1 to 6, the second lens unit U2 is composed of three negative lenses and one positive lens. In the zoom lens of Example 7, the second lens unit U2 is composed of two negative lenses and one positive lens, and at least one of the lenses is an aspheric lens. As a result, it is possible to suppress the decrease in optical performance while reducing the number of lenses constituting the second lens unit U2.

  In the zoom lenses of Embodiments 1 to 4, 6 and 7, the third lens unit U3 is composed of, in order from the object side to the image side, a positive lens and a negative lens. By arranging the positive lens and the negative lens in order from the object side to the image side, the distance between principal points of the third lens unit U3 and the fourth lens unit U4 can be increased, and the movement amount of the fourth lens unit U4 can be reduced. can do. As a result, it can contribute to shortening of the overall lens length.

  In the zoom lens of Embodiment 5, the third lens unit U3 is composed of, in order from the object side to the image side, a positive lens, a positive lens, and a negative lens. By arranging two positive lenses, positive refractive power is shared by a plurality of positive lenses, and fluctuation of various aberrations generated in each lens is suppressed with zooming.

  In the zoom lenses of the first to fourth, sixth, and seventh embodiments, the fourth lens unit U4 is composed of a cemented lens in which a positive lens and a negative lens are cemented in order from the object side to the image side. By using a positive lens and a negative lens, it is possible to suppress the variation in chromatic aberration associated with zooming.

  In the zoom lens of Embodiment 5, the fourth lens unit U4 is composed of, in order from the object side to the image side, a cemented lens in which a positive lens and a negative lens are cemented, and a positive lens. By arranging two positive lenses, positive refractive power is shared by a plurality of positive lenses, and fluctuation of various aberrations generated in each lens is suppressed with zooming.

  Next, lens data according to Numerical Embodiments 1 to 7 respectively corresponding to Embodiments 1 to 7 of the present invention will be shown. In each numerical example, i shows the order of the optical surface from the object side. ri is the radius of curvature of the ith optical surface (the ith surface), di is the distance between the ith surface and the (i + 1) th surface, ndi and と di are the refractions of the material of the ith optical member with respect to the d line Indicates the rate and Abbe number.

In addition, K is eccentricity, A3, A4, A5, A6, A7, A8, A9 and A10 are aspheric coefficients, and displacement in the optical axis direction at the position of height h from the optical axis is based on the surface vertex x The aspheric shape is
^{x = (h 2 / R)} / [1+ [1- (1 + K) (h / R) 2] 1/2] + A3h 3 + A4h 4 + A5h 5 + A6h 6 + A7h 7 + A8h 8 + A9h 9 + A10h 10
Is displayed. Where R is a paraxial radius of curvature. Moreover, the display of " ^eZ " means "10-Z."

  In each embodiment, the back focus (BF) represents the distance from the surface closest to the image side of the lens system to the image plane by an air-converted length. Table 1 shows the correspondence with the above-described conditional expressions in each numerical example.

  The effective image circle diameter (diameter of the image circle) at the wide angle end can be smaller than the effective image circle diameter at the telephoto end. This is because the barrel distortion that is likely to occur on the wide-angle side can be corrected by stretching the image by image processing.

Numerical Embodiment 1
Unit mm
Surface data surface number rd nd d d
1 55.000 1.25 1.85478 24.8
2 32.797 5.73 1.49700 81.5
3 279.125 0.15
4 34.086 3.95 1.49700 81.5
5 134.865 0.10
6 30.111 2.67 1.69680 55.5
7 63.538 (variable)
8 54.884 0.50 1.95375 32.3
9 6.097 2.16
10 30.843 0.45 1.83481 42.7
11 16.287 1.52
12 -16.393 0.45 1.83481 42.7
13 33.793 0.15
14 16.874 1.72 1.95906 17.5
15-48. 857 (variable)
16 (F-stop) 1.00 1.00
17 * 10.691 4.72 1.58313 59.5
18 *-24.394 1.46
19 21.604 0.50 2.00069 25.5
20 10.450 (variable)
21 18.509 3.90 1.60311 60.6
22-10.164 0.50 2.00069 25.5
23-17.092 (variable)
24 1. 1.50 1.51500 70.0
25 3. 3.80
Image plane ∞

Aspheric surface data plane 17
K = -1.02686e + 000
A 3 = -1.84598e-005 A 5 = 2.58119e-006 A 7 = 1.17540e-008

18th
K = -1.21069e + 001
A3 = -3.21956e-005 A5 = 4.61800e-006 A7 = -1.59425e-008

Various data zoom ratio 24.95
Wide-angle Intermediate telephoto focal length 4.82 41.91 120.36
F number 1.65 3.58 4.00
Half angle of view (degrees) 33.97 4.43 1.55
Image height 3.25 3.25 3.25
Lens total length 84.60 84.60 84.60
BF 12.58 20.01 6.84

d 7 0.60 21.88 26.55
d15 27.32 6.04 1.37
d20 11.23 3.80 16.97
d23 7.79 15.22 2.05

Zoom lens group data group Start focal length
1 1 39.03
2 8-6.26
3 17 24.31
4 21 19.79

Numerical Embodiment 2
Unit mm
Surface data surface number rd nd d d
1 76.044 1.70 1.85478 24.8
2 44.859 8.08 1.49700 81.5
3 445.709 0.21
4 45.918 5.07 1.49700 81.5
5 210. 585 0.14
6 41.227 3.17 1.69680 55.5
7 88.862 (variable)
8 125.485 0.70 1.95375 32.3
9 9.448 3.33
10 66.994 0.60 1.83481 42.7
11 19.181 2.69
12 -20.299 0.60 1.83481 42.7
13 3199.020 0.15
14 33.079 2.16 1.95906 17.5
15 -46.222 (variable)
16 (F-stop) ∞ (Variable)
17 * 12.189 5.17 1.58313 59.5
18 *-50.490 2.45
19 19.252 0.70 2.00069 25.5
20 10.749 (variable)
21 * 18.657 4.00 1.55332 71.7
22 -13.126 0.70 2.00069 25.5
23-21. 373 (variable)
24 2.0 2.08 1.51500 70.0
25 3. 3.80
Image plane ∞

Aspheric surface data plane 17
K = -9.57390e-001
A 3 = 1.37191 e-005 A 5 = 9.43502 e-007 A 7 = 8.81440 e-009

18th
K = -1.50396e + 001
A 3 = 2.99 426 e-005 A 5 = 2.2 0054 e-006 A 7 =-4.8 2016 e-009

21st
K = -2.48870e-001 A 4 =-4.40444e-006 A 6 = 7.36682e-009 A 8 = 5. 76115e-010

Various data Zoom ratio 22.99
Wide-angle Intermediate telephoto focal length 5.62 45.70 129.22
F number 1.65 3.17 3.50
Half angle of view (degrees) 38.68 5.62 1.99
Image height 4.50 4.50 4.50
Lens total length 109.41 109.41 109.41
BF 14.64 22.05 11.21

d 7 0.60 28.41 34.52
d15 34.95 7.14 1.04
d16 6.71 3.64 1.00
d20 10.89 6.54 20.03
d23 9.47 16.87 6.04

Zoom lens group data group Start focal length
1 1 51.64
2 8-8.91
3 17 31.48
4 21 24.12

Numerical Embodiment 3
Unit mm
Surface data surface number rd nd d d
1 60.034 1.25 1.85478 24.8
2 36.361 5.83 1.49700 81.5
3 302.800 0.15
4 38.769 3.75 1.59522 67.7
5 120.928 0.10
6 32.197 2.96 1.59522 67.7
7 72.003 (variable)
8 59.450 0.50 1.95375 32.3
9 6.419 2.12
10 26.411 0.45 1.9108 2 35.3
11 13.903 1.81
12 -14.972 0.45 1.91082 35.3
13 74.173 0.15
14 20.961 1.87 1.95906 17.5
15 -28.794 (variable)
16 (F-stop) 1.00 1.00
17 * 11.204 4.81 1.58313 59.5
18 *-25.488 1.60
19 22.684 0.50 2.00069 25.5
20 10.786 (variable)
21 19.694 3.84 1.60311 60.6
22-10.624 0.50 2.00069 25.5
23-17.536 (variable)
24 1. 1.50 1.51500 70.0
25 3. 3.80
Image plane ∞

Aspheric surface data plane 17
K = -1.09931e + 000
A 3 = 7.88892e-007 A 5 = 2.87708e-006 A 7 = 2.26419e-009

18th
K = -1.15637e + 001
A3 = -1.23300e-005 A5 = 3.64844e-006 A7 = -1.41845e-008

Various data Zoom ratio 27.93
Wide-angle Intermediate telephoto focal length 4.76 43.30 132.90
F number 1.65 3.58 4.00
Half angle of view (degrees) 34.33 4.29 1.40
Image height 3.25 3.25 3.25
Lens total length 89.58 89.58 89.58
BF 12.98 20.86 6.84

d 7 0.60 24.71 30.00
d15 30.54 6.44 1.15
d20 11.81 3.93 17.95
d23 8.19 16.07 2.05

Zoom lens group data group Start focal length
1 1 43.09
2 8-6.72
3 17 26.11
4 21 20.46

Numerical Embodiment 4
Unit mm
Surface data surface number rd nd d d
1 57.193 1.25 1.85478 24.8
2 30.473 5.85 1.49700 81.5
3 216.927 0.15
4 33.402 3.81 1.69680 55.5
5 111.160 0.10
6 32.975 2.42 1.69680 55.5
7 65.793 (variable)
8 57.135 0.50 1.95375 32.3
9 6.353 2.17
10 29.455 0.45 1.83481 42.7
11 16.502 1.59
12-16.630 0.45 1.83481 42.7
13 33.212 0.15
14 17.374 1.75 1.95906 17.5
15-48.984 (variable)
16 (F-stop) 1.00 1.00
17 * 9.702 4.58 1.58313 59.5
18 *-27.502 1.51
19 17.893 0.50 2.00069 25.5
20 9.080 (variable)
21 16.234 3.85 1.60311 60.6
22 -9.778 0.50 2.00069 25.5
23-16.945 (variable)
24 1. 1.50 1.51500 70.0
25 3. 3.80
Image plane ∞

Aspheric surface data plane 17
K = -1.00320e + 000
A3 = -2.97831e-006 A5 = 3.22092e-006 A7 = 2.35371e-008

18th
K = -1.41855e + 001
A 3 = 2.51531e-006 A 5 = 6.01040e-006 A 7 =-2.41285e-008

Various data zoom ratio 21.97
Wide-angle Intermediate telephoto focal length 4.78 39.36 105.09
F number 1.65 3.17 3.50
Half angle of view (degrees) 34.19 4.72 1.77
Image height 3.25 3.25 3.25
Lens total length 81.56 81.56 81.56
BF 11.65 17.90 6.84

d 7 0.60 21.51 26.09
d15 26.85 5.94 1.36
d20 9.88 3.63 14.69
d23 6.86 13.11 2.05

Zoom lens group data group Start focal length
1 1 38.54
2 8 -6.49
3 17 23.60
4 21 18.55

Numerical Embodiment 5
Unit mm
Surface data surface number rd nd d d
1 56.799 1.25 1.84666 23.8
2 34.251 5.31 1.49700 81.5
3 279.634 0.15
4 36.185 3.55 1.49700 81.5
5 139.790 0.10
6 29.719 2.80 1.69680 55.5
7 64.004 (variable)
8 45.698 0.60 2.00100 29.1
9 5.822 3.65
10 * -48.405 0.60 1.76802 49.2
11 * 35.061 0.12
12 43.892 0.50 1.91082 35.3
13 11.450 2.17 1.95906 17.5
14-132.546 (variable)
15 (F-stop) ∞ 1.00
16 * 10.559 4.17 1.69350 53.2
17 *-40.951 0.18
18 18.894 0.91 1.60311 60.6
19 25.147 0.60 2.00100 29.1
20 9.225 (variable)
21 19.776 3.57 1.60311 60.6
22-10.881 0.60 2.00069 25.5
23-22.189 0.15
24 -118.535 1.28 1.51633 64.1
25-24.533 (variable)
26 1. 1.50 1.51500 70.0
27 3. 3.80
Image plane ∞

Aspheric surface data surface 10
K = 9.13879e + 001 A 4 = -1.22707e-003 A 6 = 3.20881e-005 A 8 =-3.80905e-007
A10 = -1.69004e-008

11th
K = -2.332309e + 001 A 4 =-1.420060e-003 A 6 = 3.44555e-005 A 8 =-7.89692e-007
A10 = -5.23523e-009

16th
K = -4.38690e-001 A 4 = -4.08007e-005 A 6 = 7.92561e-008 A 8 = 4.38561e-009
A10 = -7.57322e-011

17th
K = 1.23404e + 001 A 4 = 9.72088e-005 A 6 = 1.63501e-007 A 8 =-2.03402e-009
A10 = -1.33408e-011

Various data Zoom ratio 23.92
Wide-angle Intermediate telephoto focal length 4.85 39.12 116.09
F number 1.65 3.49 4.00
Half angle of view (degrees) 33.81 4.75 1.60
Image height 3.25 3.25 3.25
Lens total length 84.40 84.40 84.40
BF 12.52 19.57 6.79

d 7 0.60 21.55 26.79
d14 27.19 6.24 1.00
d20 10.82 3.77 16.55
d25 7.73 14.78 2.00

Zoom lens group data group Start focal length
1 1 39.30
2 8 -6.49
3 16 25.48
4 21 18.73

Numerical Embodiment 6
Unit mm
Surface data surface number rd nd d d
1 60.317 1.25 1.85478 24.8
2 35.901 5.76 1.49700 81.5
3 324.865 0.15
4 38.164 3.78 1.49700 81.5
5 129.226 0.10
6 33.475 2.83 1.69680 55.5
7 75.447 (variable)
8 43.553 0.50 2.00100 29.1
9 6.525 3.36
10 -22.286 0.45 1.83481 42.7
11 24.635 0.51
12 14.8.89 2.14 1.95906 17.5
13-44.025 0.45 1.9108 2 35.3
14 83.683 (variable)
15 (F-stop) ∞ 1.00
16 * 10.746 4.81 1.58313 59.5
17 * -29.106 1.34
18 19.418 0.50 2.00069 25.5
19 10.168 (variable)
20 18.284 3.84 1.60311 60.6
21 -10.896 0.50 2.00069 25.5
22 -18.746 (variable)
23 1. 1.50 1.51500 70.0
24 3. 3.80
Image plane ∞

Aspheric surface data surface 16
K = -9.98410e-001
A 3 = 1.84306e-006 A 5 = 2.00870e-006 A 7 = 1.10851e-008

17th
K = -1.43239e + 001
A 3 = 2.84299e-006 A 5 = 3.54144e-006 A 7 =-1.14178e-008

Various data Zoom ratio 26.95
Wide-angle Intermediate telephoto focal length 4.85 44.37 130.72
F number 1.65 3.58 4.00
Half angle of view (degrees) 33.83 4.19 1.42
Image height 3.25 3.25 3.25
Lens total length 89.55 89.55 89.55
BF 12.74 20.85 6.84

d 7 0.60 24.67 29.96
d14 30.77 6.69 1.41
d19 12.18 4.07 18.08
d22 7.95 16.06 2.05

Zoom lens group data group Start focal length
1 1 43.13
2 8-6.77
3 16 25.66
4 20 20.60

Numerical Embodiment 7
Unit mm
Surface data surface number rd nd d d
1 58.667 1.25 1.85478 24.8
2 34.815 5.80 1.49700 81.5
3 363.768 0.15
4 36.159 3.77 1.49700 81.5
5 119.284 0.10
6 32.168 2.75 1.69680 55.5
7 71.570 (variable)
8 49.221 0.50 1.95375 32.3
9 6.230 3.81
10 * -15.054 0.45 1.85135 40.1
11 * 26.942 0.53
12 24.970 1.76 1.95906 17.5
13-31.085 (variable)
14 (F-stop) ∞ 1.00
15 * 10.145 4.59 1.58313 59.5
16 *-28.390 1.81
17 19.093 0.50 2.00069 25.5
18 9.428 (variable)
19 16.746 3.90 1.60311 60.6
20-10.021 0.50 2.0 0069 25.5
21-17.101 (variable)
22 1. 1.50 1.51500 70.0
23 3. 3.80
Image plane ∞

Aspheric surface data surface 10
K = 1.63600 e + 000 A 4 = −5.81393 e-005 A 6 = −6.42552 e-008 A 8 = −7.21516 e-008

11th
K = -2.43612e + 001 A 4 = -6.17765e-005 A 6 = -2.06892e-006 A 8 = -1.18192e-009

15th
K = -1.05765e + 000
A 3 = 1.14761e-005 A 5 = 3.80400e-006 A 7 = 7.82312e-009

16th
K = -1.42800e + 001
A 3 = 6.34898e-006 A 5 = 4.89347e-006 A 7 =-2.17641e-008

Various data zoom ratio 22.97
Wide-angle Intermediate telephoto focal length 4.82 40.34 110.69
F number 1.65 3.17 3.50
Half angle of view (degrees) 34.00 4.61 1.68
Image height 3.25 3.25 3.25
Lens total length 84.52 84.52 84.52
BF 11.91 18.18 6.84

d 7 0.60 23.36 28.35
d13 28.93 6.17 1.17
d18 9.91 3.63 14.98
d21 7.12 13.39 2.05

Zoom lens group data group Start focal length
1 1 41.39
2 8-6.95
3 15 24.98
4 19 18.79

  Next, an embodiment of a surveillance camera using the zoom lens according to the present invention as a photographing optical system will be described with reference to FIG.

  In FIG. 15, reference numeral 30 denotes a monitoring camera main body, and reference numeral 31 denotes a photographing optical system constituted by any of the zoom lenses described in the first to ninth embodiments. Reference numeral 32 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor which is built in the camera body and receives an object image formed by the photographing optical system 31. Reference numeral 33 denotes a memory for recording information corresponding to a subject image photoelectrically converted by the solid-state imaging device 32. Reference numeral 34 denotes a network cable for transferring a subject image photoelectrically converted by the solid-state imaging device 32.

  As described above, by applying the zoom lens of the present invention to an imaging device such as a digital still camera, it is possible to obtain an imaging device which is compact and has high magnification and high optical performance.

U1 First lens unit U2 Second lens unit U3 Third lens unit U4 Fourth lens unit SP Aperture G Optical block IP Image plane

Claims (19)

A first lens group of positive refractive power, a second lens group of negative refractive power, a third lens group of positive refractive power, and a fourth lens group of positive refractive power, arranged in order from the object side to the image side During zooming from the wide-angle end to the telephoto end, the first lens group is stationary, and at least the second lens group and the fourth lens group move, and the distance between adjacent lens groups changes during zooming A zoom lens,
The first lens unit includes a negative lens, a positive lens, a positive lens, and a positive lens, which are disposed in order from the object side to the image side.
The second lens group is composed of two negative lenses and one positive lens ,
Assuming that the Abbe number of the material of the positive lens disposed in the first lens group is d d1 p
The first lens group is
74.0 <νd1p <100.0
It has a positive lens satisfying the following conditional expression,
The focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the third lens group is f3, the focal length of the fourth lens group is f4, and the entire system at the wide-angle end The focal length is fw, the lateral magnification of the second lens group is β2t when the object at infinity is in focus at the telephoto end, and the Abbe number of the material of the positive lens disposed in the second lens group is dd2p . When
-7.30 <f1 / f2 <-4.60
1.16 <f3 / f4 <1.55
3.80 <f4 / fw <6.50
−12.00 <β2t <−5.50
10.0 <νd2p <21.0
A zoom lens characterized by satisfying the following conditional expression. The most object lens disposed side of the second lens group is a negative lens, when the refractive index relative to the d-line of the second lens group on the most object side lens disposed as Nd2n1,
nd2n1> 1.900
The zoom lens according to claim 1, which satisfies the following conditional expression. Assuming that the distance on the optical axis from the lens surface closest to the object side of the first lens group to the image plane is TL, and the focal length of the entire system at the telephoto end is ft
0.070 <(TL / f1) / (ft / fw) <0.100
The zoom lens according to claim 1 or 2, wherein the following conditional expression is satisfied. Assuming that the distance on the optical axis from the lens surface closest to the object side of the first lens group to the image plane is TL, the effective image circle radius at the telephoto end is φt, and the focal length of the entire system at the telephoto end is ft.
0.95 <(TL / φt) / (ft / fw) <1.20
The zoom lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied. When the back focus at the wide angle end is BFw,
1.30 <BFw / fw <4.00
The zoom lens according to any one of claims 1 to 4, wherein the following conditional expression is satisfied. Assuming that the lateral magnification of the second lens unit is β2 w when an object at infinity is in focus at the wide-angle end,
21.0 <β2t / β2w <45.0
The zoom lens according to any one of claims 1 to 5, wherein the following conditional expression is satisfied. The lateral magnification of the fourth lens group is β4 w when focusing on an object at infinity at the wide angle end, and β4 t is the lateral magnification of the fourth lens group when focusing at an object at infinity at the telephoto end. When you
1.30 <β4t / β4w <2.60
The zoom lens according to any one of claims 1 to 6, wherein the following conditional expression is satisfied. When the distance on the optical axis from the lens surface on the most object side of the first lens group to the image plane is TL, and the distance on the optical axis between the first lens group and the second lens group at the wide angle end is L1 w ,
0.000 <L1w / TL <0.020
The zoom lens according to any one of claims 1 to 7, wherein the following conditional expression is satisfied. When the distance on the optical axis from the lens surface closest to the object side of the first lens group to the image plane is TL, and the distance between the second lens group and the third lens group at the telephoto end on the optical axis is L2t ,
0.000 <L2t / TL <0.050
The zoom lens according to any one of claims 1 to 8, satisfying the following conditional expression. Before SL least one lens included in the second lens group, the zoom lens according to any one of claims 1 to 9, characterized in that it has a lens surface of aspherical shape. The third lens group, disposed in order from the object side to the image side, a positive lens, a zoom lens according to any one of claims 1 to 10, characterized in Tei Rukoto consists negative lens. The zoom lens according to any one of claims 1 to 11 , wherein the fourth lens group is configured of one positive lens and one negative lens. A first lens group of positive refractive power, a second lens group of negative refractive power, a third lens group of positive refractive power, and a fourth lens group of positive refractive power, arranged in order from the object side to the image side During zooming from the wide-angle end to the telephoto end, the first lens group is stationary, and at least the second lens group and the fourth lens group move, and the distance between adjacent lens groups changes during zooming A zoom lens,
The first lens unit includes a negative lens, a positive lens, a positive lens, and a positive lens, which are disposed in order from the object side to the image side.
The second lens group has three or more lens elements including at least one positive lens,
The third lens unit includes a positive lens, a positive lens, and a negative lens, which are disposed in order from the object side to the image side.
The Abbe number of the material of the positive lens disposed in the first lens group is dd1p, and the Abbe number of the material of the positive lens disposed in the second lens group is を d2p.
The first lens group is
74.0 <νd1p <100.0
Have a positive lens that satisfies the conditional expression
The second lens group is
10.0 <νd2p <21.0
Have a positive lens that satisfies the conditional expression
The focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the third lens group is f3, the focal length of the fourth lens group is f4, and the entire system at the wide-angle end Assuming that the focal length is fw, and the lateral magnification of the second lens unit when focusing on an object at infinity at the telephoto end is β2t,
-7.30 <f1 / f2 <-4.60
1.16 <f3 / f4 <1.55
3.80 <f4 / fw <6.50
−12.00 <β2t <−5.50
A zoom lens characterized by satisfying the following conditional expression. The zoom lens according to claim 13, wherein the second lens group is configured of three negative lenses and one positive lens. 15. The zoom lens according to claim 13, wherein the fourth lens group is composed of two or more positive lenses and one negative lens. The zoom lens according to any one of claims 1 to 15, wherein at least one lens included in the third lens group has an aspheric lens surface. An image pickup apparatus comprising: the zoom lens according to any one of claims 1 to 16 ; and an image pickup element for receiving an image formed by the zoom lens. The imaging device according to claim 17, wherein the imaging device is connected to a network cable for transferring an image generated by the imaging device. The imaging device according to claim 17 or 18, wherein the imaging device is a surveillance camera.